Terminal structure for electric lamps



April 3' c. A. COTMAN ETAL TERMINAL STRUCTURE FOR ELECTRIC LAMPSlnvewtors: Carl A. Cowman, DanieL KMQWC, b5 Their A'tcorneg Filed April9. 1942 Patented Apr. 20, 1943 2.31am TERMINAL s'rnvc'roas roa smormcram-s can A. Cotman and Daniel K. Wright, Cleveland Heights, Ohio,assignors to General Electrio Company, a corporation of New YorkApplication April 9, 1942, Serial No. 438,348

9 Claims. (Cl. 176-32) Our invention relates to electric incandescentlamps and similar devices comprising a bulb having one or moreelectrical energy translation elements sealed therein and a base mountedon said bulb. More particularly, our invention relates to a base orterminal structure for such devices and particularly for the devicedisclosed in our copending application Serial No. 402,120, filed July12, 1941, of which the present application is a continuation-impart.

. One object of our invention is to provide an electrical device havinga base or terminal arrangement which is simple in construction andrelatively inexpensive, and which is firmly secured to the envelope ofthe device by mechanical means.

Another object of our invention is to provide a unitary and rigid basestructure for connection to the terminal elements of electrical devicesof the above type, the said base serving to minimize the various strainsto which the said terminal ele ments are subjected during the use of thedevice.

Still another object of our invention is to provide a base structure forelectrical devices of the above type which is formed of a minimum numberof parts and a. minimum amount of material, and which serves to protectthe exhaust tip extending from the envelope of the device.

Further objects and advantages of our invention will appear from thefollowing description of species thereof and from the accompanying.

drawing in which:

Fig. 1 is a side elevation, partly in section, of an electricincandescent lamp provided with a base and terminal arrangementcomprising our invention; Fig. 2 is a fragmentary rear elevation of thebase portion of the lamp shown in Fig. 1;

Fig. 3 is a fragmentary perspective view of the base portion of the lampshown in Fig. 1; Fig. 4 is a fragmentary sectional view, on an enlargedscale, of a modified form of base according to our invention; Fig. 5 isa fragmentary rear elevation and Fig. 6 is a perspective view of themodifled lamp base shown in Fig. 4

Referring to the drawing, the lamp there shown is of the sealed beamtype such as described and claimed in U. S. Patents 2,148,314 and2,148,315, issued February 21, 1939, to D. K. Wright, and comprises asealed glass bulb or envelope i0 consisting of a preformed pressed glassconcave reflector section i l of heat resisting glass and a cover glassor lens section I! also of heat resisting pressed glass sealed togetherat their peripheries by fusion. The interior surface I 3 of thereflector section H is of any suitable optical shape, preferably that ofa paraboloid, and is covered with a reflecting metallic coating I4,preferably aluminum, so as to form a reflecting surface. The exterior ofthe reflector section I i, adjacent the apex thereof, is formed withthree glass bosses l5 arranged in triangular formation about the apex ofthe reflector section, as shown in Fig. 2, two of the bosses beingdisposed on opposite sides of the apex of said reflector and the otherboss being disposed directly above said apex. Each of the bosses i5 isprovided with a concentric opening it extending through the wall of thereflector section and communicating with the interior oi the lampenvelope l0.

Mounted within the envelope iii in definite optical relation totherefiecting surface it thereof, is a pair of spaced electrical energytranslation elements or filaments l1, l8, preferably in the form ofconcentrated linear coils of a suitable metallic refractory material,such as tungsten. The said filaments are arranged parallel to oneanother in more or less side-by-side relation and in the focal plane ofthe parabolic reflecting surface M, with one filament i! (the majorfilament) disposed at the focal point of the reflecting surface it andthe other filament I8 (the minor filament) offset a slight distanceabove and to one side of the said focal point. The filaments aresupported within the bulb ill by, and electrically connected at theirends to, a plurality of relatively heavy rigid leading-in wires l9 whichextend through the openings IS in the reflector section to a plurality(3) of closed metal cups or thimbles 20 mounted on the exterior of thereflector section, with their axes parallel to the axis of the reflectorsection I I, and each covering one of the openings l6 therein.

The said thimbles 20 have their edges or rims fused to and sunk andembedded in the glass of the bosses 5 so as to form a hermetic sealtherebetween, similar to that described and claimed in U. S. Patent2,098,080 D. K. Wright, issued November 2, 193?.

The cups or thimbles 20 are made of a metal to which the glass of thelamp envelope ID will wet or adhere, and should preferably have anexpansion as near as possible to that of the glass. For heat-resistantglass of the type known as Pyrex," the thimbles 20 are preferably madeeither of an iron-nickel-cobalt alloy known as Fernico or an iron-nickelalloy containing approximately 42 per cent nickel. Each of the metalthimbles 20 is formed with a small tubular projection or nipple 2iextending outwardly from the outer end of the thimble. The inner wireleads 18 extend into the thimble 20 and are firmly securedthereto bymeans of a suitable metallic fusible material 22, such as hard solder,so as to provide an electrical connection between the leading-in wiresand the metal cups as well as a firm support for the said wires and thefilaments ll, l8.

The lamp envelope I9 is exhausted and filled with a suitable gas, suchas argon or nitrogen or mixtures thereof, through an exhaust tube 23attached to the reflector section at the apex thereof and communicatingwith the interior of the lamp envelope through an opening 24 extendingthrough the wall of the reflector section through the apexthereof. Afterthe gas filling, is introduced into the lamp envelope, the exhaust tube23 is tipped off to provide a flattened tip 25, as.

shown in the drawing. Theflattened exhaust tube tip 25 is disposed inaplane at an angle to the plane passing through the axes of the twodiametrically opposite metal thimbles 20.

Mounted on the metal thimbles is a lamp base or terminal structure 28comprising our invention. The said base structure 20 comprises a smallrectangular plate-shaped body member 2! of suitable insulating material,and a plurality (three) of L-shaped metal contact lugs or prong members28 each secured to the insulator member 21 and to one of the metalthimbles 20. The insulator plate member 21 may be made, for instance, ofa suitable plastic material, such as, for instance, those commerciallyknown as Textolite, Bakelite, etc.

The L-shaped contact prongs 28 are formed with mounting leg portions 29and connector leg portions 30, and are mounted on the insulator platemember 21 in triangularformation thereon with the said connector legportions 30 extending perpendicularly outward in the same direction fromone of the surfaces of the plate-shaped insulator member 21. Theconnector leg portions 30 extend through the insulator member 21 throughsuitable openings 3| therein, and are each provided.with a bendablelocking lug or tongue 32 which is punched out of the said connector legportion 30 and is bent-over against the insulator member 21 so as toextend in a direction the same as the mounting leg 29 and firmly clampsaid member 21 between the mounting leg portion 29 and the said lockinglug or tab 32 of each contact prong. The mounting leg portions 29 of thecontact prongs 28 extend outwardly from the connector leg portions 30and project from the edges of the insulator member 21 so as to formprojecting ear portions which are provided with integral eyelets 33(Fig. 1)

.punched therefrom, the said eyelets being of wardly from the envelopeina direction parallel to the axis of the reflector section II, as shownin Figs. 1 and 3, and with the contact'prong eyelets 33 fitting over thenipples2'l on the. thimbles 20 and secured thereto by clamping, or by areadily fusible metallic material 34 such as solder, as shown. In thisway a firm'and secure mounting portant where the lamp terminal elementsare of the two-piece type, such as disclosed in United States Patent2,098,080 D. K. Wright, issued November 2, 1937, in which a terminalpost extends through the thimble 20 and is brazed thereto. In such case,the distribution of the strains to all three of such two-piece terminalelements serves to minirriize the possibility of the brazed jointbetween the two parts of any one of said elements becoming loosened andseparated by such strains with resultant destruction of the hermeticseal between such parts.

.The insulator member'2l, which is disposed across the rear or thimbledportion of the reflector section II, therefore more Or less overlies thetipped exhaust tube 23 so as to protect and shield the same from impactswhich might cause breakage of said tube. The said insulating member,however, is provided with an elongated opening or aperture 35 adjacentits middle portion, which opening extends diagonally of therectangular-shaped insulator member so as to be in alignment with andtherefore accommodate the flattened exhaust tube tip 25 should thelatter extend too far out from the lamp envelope l0.

Referring to Figs. 4-6, the modified base construction 36 there shown issimilar to the base of the base on the lamp envelope III is provided;

The insulator member 21 serves to distribute any forces to which thecontact prongs 28.may be subjected during service of the lamp, toall'three of the contact prongs and therefore to all three of the solderjoints or connections between said prongs and the thimbles 2|, thusminimizing the possibility of rupture of the saidsolder joints.

This strain-distributingfeature is especially im- 76 26 shown in Figs.1-3 but differs therefrom in the size and shape of the insulator member31 and in the manner of attachment of the contact prongs 28 to saidmember. The insulator member 31 of the modified base construction is ofmore or less triangular shape, as shown particularly in Figs. 5 and 6,and is somewhat larger than the rectangular insulator 21 of Figs. 1 -3,the said member 31 being sufiiciently large to at least surround theintegral eyelets 33 on the rzrgounting leg portions 29 of the contactprongs The contact prongs 28 are mounted on the insulator member 31 inthe same triangular manner as in the previous form of the invention, butwith the mounting legs 29 engaging the upper or top surface 38 of theinsulator instead of the under surfaceas before. The eyelets 33 on themounting legs 29 extend through the insulator 31 through suitableopenings therein, and are rolled or peaned over onto the under surface39 of said member to thereby provide a firm attachment of each contactprong 28 to the insulator member at a point adjacent the free end of theso as to extend from the mounting leg portion 29 in a direction oppositeto that of the connector leg portion 30. The locking lugsor tabs 40 ex-.

tend through suitable openings in the insulator a member 3! and are bentover onto the under'sur face 39 of saidmember, preferably in adirection,-

oppositeto that of the mounting-legs 29, so as to I firmly clamp thecontact prongs to theinsulator member 31; -The eyelets- 33 and lockinglugs thusprovide a two-point, and therefore stronger, attachment orsupport of each'contact prong 28 on'the insulator member 31.

The modified base 36 is mounted on the lamp envelope ill in the same wayas the base 26,- i. e.,

with'the connector leg portions 38 of the conreflector section II, andwith the contact prong eyelets 33 fitting over the nipples 2| n thethimbles and secured thereto byclampinz, or by solder 34 as shown. As inthe previous form of the invention, the insulating body member 31 servesto insulate the three contact prongs 28 and to distribute any strainsimposed on such prongs to all three points of connection between thebase and the three thimbles 20. Likewise, the insulator 31, whichextends across the rear or thimbled portion of the reflector section IIso as to more or less overlie the tipped exhaust tube 23 and thereforeprotect or shield the same from impacts which might cause its breakage,is also provided with an opening or aperture 4| adjacent its middleportion for the accommodation therein cf the exhaust tube tip 25 shouldthe latter extend an excessive distance out from'the lamp envelope I 0.

What we claim as new and desire to secure by Letters Patent of theUnited States is:

1. An electrical device comprising a'glass envelope having a pluralityof metal terminal elements mounted exteriorly of said envelope and eachprovided with a cylindrical extension, and a base structure for saiddevice comprising an insulator member and a plurality of metal contactprongs rigidly secured to said insulator member, said contact prongshavingintegral eyelets fitting over the said extensions on said terminalelements and being rigidly secured thereto.

and having their edges fused into a wall of said envelope aroundopenings therein, said cup members having cylindrical extensions andbeing imperforate so as to hermetically seal said openings, and a basestructure for said device comprising an insulator member and a pluralityof metal contact prongs rigidly secured to said insulator member, saidcontact prongs having integral eyelets fitting over the said extensionson said cup members and being rigidly secured thereto.

3. An electrical device comprising a glass envelope having a pluralityof metal terminal elements mounted exteriorly of said envelope and eachprovided with a cylindrical extension, a tipped exhaust tube extendingoutwardly from said envelope at a point between said terminal elements,and a base structure for said device comprising an insulator memberdisposed between said terminal elements so as to shield said exhausttube and having an aperture for the accommodation of the tip of saidexhaust tube, and a plurality of metal contact prongs rigidly secured tosaid insulator member and provided with integral eyelets fitting overthe said extensions on said terminal elements and rigidly securedthereto.

4. An electrical device comprising a glass envelope having three metalterminal elements mounted exteriorly of said envelope in triangularformation thereon and each provided with a ctlindrical extension, and abase structure for said device comprising an insulator plate member andthree metal contact prongs rigidly secured to said insulator plate intriangular formation corresponding to that of the terminal elements onsaid envelope, said contact prongs having portions projecting outwardlyof the edges of said insulator plate and provided with integral eyeletsfitting over the said extensions on said terminal elements and rigidlysecured thereto.

5. An electrical device comprising a glass envelope having three metalterminal elements mounted exteriorly of said envelope in triangularformation thereon and each provided with 9. cy-

lindrical extension, and a base structure for said device comprising aninsulator plate member and three L-shaped metal contact prongs mountedon said insulator plate in triangular formation thereon, each of saidL-shaped contact prongs having one leg thereof extending through andprojecting perpendicularly outward from said insulator plate andprovided with a locking lug bent over onto said insulator plate tothereby firmly clamp said prong to said insulator plate, and the otherlegs of said prongs projecting outwardly beyond the edges of saidinsulator plate and having integral eyelets punched out of the saidprojecting portions thereof, said eyelets fitting over the saidextensions on said terminal elements and being rigidly secured tlereto.

6. An electrical device comprising a glass envelope having three metalterminal elements mounted exteriorly of said envelope in triangularformation thereon and each'provided with a cylindrical extension, and abase structure for said device comprising an insulator plate member andthree L-shaped metal contact prongs mounted on said insulatorplate intriangular formation thereon, each of said L-shaped contact prongshaving one leg thereof extending perpendicularly outward from saidinsulator plate and provided with a locking lug extending through andbent over onto said insulator plate to thereby firmly clamp said prongto said insulator plate, and the other legs of said prongs havingintegral eyelets extending through said insulator plate and having theirfree rim portions peaned over onto said insulator plate to therebyfirmly clamp said prongs to said insulator plate, said eyelets fittingover the said extensions on said terminal elements and being rigidlysecured thereto.

'7. A base for an electric device comprising an insulator plate memberand a plurality of L- shaped contact prongs rigidly secured to saidinsulator plate each with one leg thereof resting flat against a surfaceof said insulator plate and the other leg thereof extendingperpendicularly outward from said insulator plate, said contact prongshaving locking lugs punched therefrom and bent over against saidinsulator plate to thereby firmly clamp said prongs to said insulatorplate, and said one of said legs having integral eyelets punchedtherefrom for engagement with terminal elements on said device.

8. A base for an electric device comprising an insulator plate memberand a plurality of L- shaped metal contact prongs rigidly secured tosaid insulator plate each with one leg thereof resting fiat against asurface of said insulator plate and the other leg extending through andprojecting perpendicularly outward from said insulator plate, saidcontact prongs having looking lugs punched therefrom and bent overagainst said insulator plate to thereby firmly clamp said prongs to saidinsulator plate, and said one of said legs projecting outwardly beyondthe edges of said insulator plate and having integral eyelets punchedout of the projecting portions thereof for engagement with terminalelements on said electric device.

9. A base for an electric device comprising an insulator plate memberand a plurality of L- shaped metal contact prongs rigidly secured tosaid insulator plate each with one leg thereof resting fiat against asurface of said insulator 4- asmosz plate and the other leg thereofextending persaid electric device, said eyelets extending pendicularlyoutward from said insulator plate, through said insulator plate andhaving their said contact prongs having bendable locking lugs free rimportions peaned over onto said insulator punched therefrom and bent overagainst said plate to thereby firmly clamp said prongs to said insulatorplate to thereby firmly clamp said 5 insulator plate. prongs to saidinsulator plate, and said one of CARL A. COTMAN.

said legs having integral eyelets punched there- DANmL K. WRIGHT. fromfor engagement with terminal elements on i V I

